81 research outputs found
Epischnomyia merzi Rohacek 2009
No full textEpischnomyia merzi Roháček, 2009 (Fig. 66) Material examined. CHINA: SICHUAN : Pingwu Co., Mianyang, Laohegou (= Old Creek), Xiaogou (= Small Valley), 32°29′02.47′′N 104°42′21.17′′E, 15.v.2016, 1814 m, 1 1 ♀ in copula on leaf, S. + S. Marshall leg. (DEBU, dried from ethanol and mounted on triangular pinned card, both genit. prep. but female body lost during drying process so only its abdomen is preserved). Remarks. The pair of specimens examined belong to the pale form of E. merzi as described by ROHÁČEK (2009: 80) having frons and medial part of mesonotum largely yellow although the latter has a pair of faint vittae in the female (see Fig. 66). This form closely resembles in colour the species E. triarmigera (Sueyoshi & Roháček, 2003) but detailed study of characters of the male and female terminalia confirmed the identity of the above Chinese specimens as E. merzi. Biology. Very little known. The type specimens were found in South Korea in forests at higher altitudes (750–1200 m) in the second half of June (ROHÁČEK 2009). The specimens from Sichuan were photographed on a small shrub in a slightly open hilltop (1814 m) surrounded by dense forest (as in Fig. 67) in May (S. A. Marshall, personal communication, 2018). The first habitat photos (see also that of E. tkoci below, Fig. 72) of Epischnomyia species in China indicate that members of this genus could be associated with dicotyledonous plants in the undergrowth of leafy forests. Distribution. South Korea (ROHÁČEK 2009), China: Sichuan (new record).Published as part of Roháček, Jindřich, 2018, First Anthomyzidae (Diptera) from China: a new genus, six new species and new records, pp. 35-76 in Acta Entomologica Musei Nationalis Pragae 58 (1) on page 57, DOI: 10.2478/aemnp-2018-0007, http://zenodo.org/record/367672
Normal matrix models and orthogonal polynomials for a class of potentials with discrete rotational symmetries
No full textIn this thesis we are going to study normal random matrix models which generalize naturally the polynomially perturbed Ginibre ensamble, focusing in particular on their eigenvalue distribution and on the asymptotics of the associated orthogonal polynomials. \\
The main result we are going to present are the following:
\begin{itemize}
\item we describe the explicit derivation of the equilibrium measure for a class of potentials with discrete rotational symmetries, namely of the form
\item We obtain the strong asymptotics for the orthogonal polynomials associated to the weight
and we will show how the density of their zeroes is related to the eigenvalue distribution of the corresponding matrix model;
\item We show how the conformal maps used to describe the support of the equilibrium measure for polynomial perturbation of the potential lead to a natural generalization of the concept of polynomial curves introduced in by Elbau.
\end{itemize
Parallelomma merzi OZEROV 2011
No full textParallelomma merzi OZEROV, 2011a D i s t r i b u t i o n: Thailand, Vietnam (OZEROV & KRIVOSHEINA 2011a). C o m m e n t: MERZ (2006: 224) cited one male of Parallelomma sp. from MHNG as "...first genus of this family recorded from Thailand ". This specimen was later described by OZEROV & KRIVOSHEINA (2011a) as a new species.Published as part of V, Marco, 2021, Annotated supplements to catalogues of the family Scathophagidae (Diptera) in the world, with new taxonomic data, notes on some species and new list of species, pp. 1267-1306 in Linzer biologische Beiträge 52 (2) on page 1274, DOI: 10.5281/zenodo.503898
Defects studies towards more-radiation-tolerant Silicon Photomultipliers
No full textSilicon photomultipliers (SiPMs) are single-photon sensitive large-area detectors widely used in many applications. Among them, they are used in several radiation-harsh applications, like high-energy physics and experiments in space, where they receive a significant radiation dose. The effect of ionizing and non-ionizing radiation dose on their performance is very interesting for those applications.We irradiated several Silicon Photomultipliers with protons and X-ray. We investigated the noise increment and directly compared per performance worsening on several SiPM technologies produced sat FBK (Trento, Italy). We also characterized the temperature dependence of the noise down to cryogenic levels, extracting the activation energy. We investigated in depth the defects created by protons within the microcells of the SiPMs, with emission microscopy measurements. We also investigated the effect of ionizing-energy-loss in the SiPM microcells, showing a relevant effect of charge accumulation in the dielectrics and in the trenches. Some technologies demonstrated a worse radiation tolerance with an internal modification of electric fields that increases the primary noise and afterpulsing. This have been directly confirmed with a dedicated irradiation campaign comparing SiPMs with different materials inside the deep trenches between microcells.All these considerations are useful to develop new SiPM technologies that are more radiation hard, both in terms of bulk damage and ionizing-energy-loss effects
Orthogonal Polynomials for a Class of Measures with Discrete Rotational Symmetries in the Complex Plane
No full textWe obtain the strong asymptotics of polynomials pn(λ), λ ∈ C, orthogonal with respect to measures in the complex plane of the forme−N(|λ|2s−tλs−tλs)dA(λ),where s is a positive integer, t is a complex parameter and dA stands for the area measure in the plane. Such problem has its origin from normal matrix models. We study the asymptotic behaviour of pn(λ) in the limit n, N → ∞ in such a way that n/N → T constant. Such asymptotic behaviour has two distinguished regimes according to the topology of the limiting support of the eigenvalues distribution of the normal matrix model. If 0 < |t| 2 < T /s, the eigenvalue distribution support is a simply connected compact set of the complex plane, while for |t| 2 > T /s the eigenvalue distribution supportconsists of s connected components. Correspondingly the support of the limiting zero distribution of the orthogonal polynomials consists of a closed contour contained in each connected component. Our asymptotic analysis is obtained by reducing the planar orthogonality conditions of the polynomialsto an equivalent contour integral orthogonality conditions. The strong asymptotics for the orthogonal polynomials is obtained from the corresponding Riemann–Hilbert problem by the Deift– Zhou nonlinear steepest descent method
Rhagoletis merzi Korneyev & Smith & Hulbert & Frey & Korneyev 2022, sp. n.
No full textRhagoletis merzi sp. n. (figs 1, c; 7–8) urn:lsid:zoobank.org:act: ADCCE1F4-7DB8-4EB6-9B5C-339A7F8F6ED9 Rhagoletis batava: Merz, 1994: 108 (misidentification); Rhagoletis flavigenualis: V. Korneyev in: Merz, 2006: 8 (misidentification); Rhagoletis sp. near flavigenualis: Korneyev et al., 2018 a: 466. T y p e m a t e r i a l. Holotype Ơ: Switzerland: Visperterminen, VS, 1400 m, 26.07.1990 (Merz) (MNHG ENTO 00012822) (MHNG). Paratypes: Switzerland: 1 ♀, Visperterminen, h = 1400 m, 17.07.1995 (Merz) (MNHG ENTO 00012824); Visperterminen, VS, 1400 m: 1 Ơ, 18.07.1993 (Merz) (MNHG ENTO 0001825); 1 Ơ, idem, 1520 m, 20.07.1993 Wald (Merz) (MNHG ENTO 0001828); 1 Ơ, idem, 17.07.1995 (Merz) (MNHG ENTO 0001823); 1 Ơ, Visperterminen, Kreuz, h = 1500 m, 21.07.2004 (Merz) (MNHG ENTO 0001827) (MHNG); Visperterminen, [Kreuz,] h = 1300–1900 m [swept from Juniperus sabina], 21.07.2004, 1 Ơ, 1 ♀ (S. & V. Korneyev) (SIZK). N o n - t y p e s p e c i m e n s. Switzerland: Visperterminen, h = 1300–1900 m, reared from Juniperus sabina fleshy cones, 3 puparia [used for DNA extraction completely], 17.10.2016 (J. Smith). D i a g n o s i s. Rhagoletis merzi is similar to all other species having the wing pattern with four dark bands, apical band joined to subapical band and separated by a crescent hyaline area from the costal vein anteroapically. It is most similar to, and in fact to our knowledge morphologically indistinguishable from, the Nearctic R. juniperina. Both species have the occiput widely black or brown on the upper 1/3, wing bands uniformly brown to blackish, mid and hind femora black, male lateral surstylus with the posterior lobe relatively short, 0.6–0.75 times as long as surstylus basal of prensisetae (fig. 8, b), and female spermathecae large, 0.09 mm in diameter, with short neck (fig. 2, f). We recognize R. merzi as a distinct species from R. juniperina based on the significant genetic distance between their COI sequences (K2P = 0.071). Rhagoletis merzi is also very similar to the Central Asian R. mongolica and R. scutellata (both known only from their holotypes, not examined for potential genitalic differences) in general appearance, including the wing pattern and having the occiput widely black on the upper 1/3. Rhagoletis mongolica is also associated with J. sabina, like R. merzi, whereas the host for R. scutellata is unknown. Rhagoletis merzi differs from R. mongolica by having black rather than yellow femora and from R. scutellata by abdominal tergites 2–4 having whitish or yellowish posterior margins and the basicostal cell brownish (in R. scutellata, basicostal cell entirely hyaline and abdominal tergites uniformly black or brown). This species readily differs from the West Palearctic R. flavigenualis and R. zernyi by having the widely black or brown median occipital sclerite, black mid and hind femora, and uniformly brown wing bands (in R. flavigenualis and R. zernyi median occipital sclerite and all femora uniformly yellow (very rarely only hind femur partly brown), and the wing bands at least partly yellow with brownish borders; R. zernyi differs also by having the discal and subapical bands widely fused). The genetic distance between R. merzi and R. flavigenualis is also significant (K2P = 0.063 –0.066). Rhagoletis merzi is similar to the Palearctic species R. bagheera and R. batava, and the Nearctic R. bushi in having the wing bands uniformly brown to blackish, and mid and hind femora black, differing from them by having the male lateral surstylus with the posterior lobe conspicuously shorter, 0.6–0.75 times as long as the surstylus basal of the prensisetae (fig. 8, b) vs. 1.3–1.4 times as long as the surstylus basal of the prensisetae in R. bagheera (fig. 3, c) and R. batava (fig. 6, a), and female spermathecae larger, 0.09 mm in diameter, with a short neck (fig. 2, f) vs. 0.02–0.03 mm in diameter, with the neck longer than the spermatheca itself in R. bagheera and R. batava. Rhagoletis merzi also has a different host plant, Juniperus sabina L., vs. Hippophae rhamnoides (Elaeagnaceae) for R. batava and Rhamnus palasii (Rhamnaceae) for R. bagheera. The genetic distance between R. merzi and R. batava is K2P = 0.064 –0.068, and between R. merzi and R. bushi K2P = 0.078 –0.079. D e s c r i p t i o n. Head. Orange-yellow, ocellar triangle, ventral part of median occipital sclerite and often occiput lateral of it black or brown. Antennal arista pubescent. Setae black except postocellar, posterior genal, and some occipital setae white. Paravertical seta short, about as long as black acuminate postocular setae. — Thorax. Scutum black, yellowish setulose, with microtrichia pattern with two pairs of partly fused matte grayish vittae separated by subshining darker areas.Postpronotal lobe and notopleural stripe creamy white to yellow; scutellum pale yellow, black on anterior margin dorsally and laterally. All thoracic setae black; basal scutellar seta inserted into black area. Halter yellow to creamy white. — Legs. Fore coxa yellow, mid and hind coxae black or brown; fore and mid trochanters yellow; hind trochanter brown or black; fore femur yellow anteroventrally, black posterodorsally; mid and hind femora black except apices yellow; hind femur somewhat thickened in male, with 2–3 longer subapical anterodorsal and 2–3 longer subapical anteroventral setae; tibiae and tarsi yellow (fig. 7). — Wing (fig. 1, c). 2.3 times as long as wide, with pattern consisting of basicostal cell with brownish tinge and four dark brown bands; subbasal band from humeral crossvein over basal half of costal cell through cells br, bm and cua (= anal cell auctt.) slightly into cell cup, discal band from pterostigma over crossvein r-m to posterior margin between veins M 4 (= CuA 1) and CuA + CuP (= CuA 1 +A 1), subapical band from middle of cell r 1 over crossvein dm-m (= dm-cu) and apical band from middle of cell r 1 into apex of cell m 4; discal band separated from both subbasal and subapical bands (figs. 1, c; 7, a) or at most narrowly fused with subapical band at posterior margin (fig. 7, c); subapical and subapical bands fused in cells r 1 and r 2+3; apical band separated from costa between apex of cell r 1 and vein M 1; no intercalary band; vein R 4+5 dorsally with 1 seta at node. — Abdomen. All segments mostly black, posterior margin of tergites 2–4 in male, and 2–5 in female narrowly creamy yellow (figs. 9, b, d). Oviscape shining black, as long as tergite 5; setae and setulae black. — G e n i t a l i a. M a l e. Epandrium black. Proctiger as long as epandrium (fig. 10, b). Surstylus dark yellow, lateral susrtylus with posterior lobe short, 0.6–0.75 times as long as surstylus basal of prensisetae (fig. 9, b). Phallus with moderately large glans (fig. 8, c) having membranous, narrow, finger-like apicodorsal process, large prepuce with smooth walls, and acrophallus with pair of semitubular filaments, very similar to that of R. bagheera (Richter & Kandybina, 1997: fig. 5), R. flavigenualis (fig. 6, c) and R. juniperina (Bush, 1966: fig. 125); preglans short and simple, without eversible caecum. Female. Eversible membrane with two pairs of taeniae 0.5 × as long as membrane itself, ventral side of membrane with scales of different size, medial ones larger than lateral ones and moderately pointed (fig. 9, g). Two globular spermathecae, 0.09 mm in diameter, with long scale-like papillae on surface (fig. 9, f). Aculeus brown, 5.5 × as long as wide, with acute apex (figs. 9, d–e). Measurements. Body length Ơ = 3.8–4.2 mm; wing length Ơ = 4.1–4.2 mm. Body length ♀ = 4.0– 4.4 mm; wing length Ơ = 3.0, wing length ♀ = 3.6 mm, costal cell length = 0.9; aculeus length = 0.85 mm; aculeus length /costal cell length = 0.9. Host plant. Juniperus sabina L. The pupae for DNA analysis were reared from the same plants and in the same locality as the type specimens were swept. D i s t r i b u t i o n. Switzerland. E t y m o l o g y. This species is named in honor of the eminent Swiss dipterist Dr.Bernhard Merz, who collected most of the type specimens, in recognition of his contributions to the study of fruit flies. Remarks. Kandybina (1977) reported specimens of “ R. mongolica ” with entirely black femora and partly black tibiae reared from Juniperus sabina in Kyrgyzstan, which need re-examination to determine whether they are conspecific with R. merzi.Published as part of Korneyev, S. V., Smith, J. J., Hulbert, D. L., Frey, J. E. & Korneyev, V. A., 2022, A New Species Of Rhagoletis (Diptera, Tephritidae) From Switzerland, With Discussion Of Its Relationships Within The Genus, pp. 1-20 in Zoodiversity 56 (1) on pages 12-15, DOI: 10.15407/zoo2022.01.001, http://zenodo.org/record/645614
Characterization of radiation damages on Silicon photomultipliers by X-rays up to 100 kGy
No full textSilicon photomultipliers (SiPMs) are highly-sensitive photodetectors emerging as the technology of choice for many applications, including among the others, large high-energy physics experiments and detectors for space instruments, where they are often exposed to a large amount of radiation. In recent years, there has been an increasing interest in assessing the performance deterioration of such detectors after ionizing and non-ionizing radiation, such as protons, neutrons and X or gamma rays. It is therefore interesting to characterize the effect of irradiation on such Geiger-mode detectors, differentiating between the ionizing and non-ionizing energy-loss effects. Moreover, it is interesting to compare the radiation damage effects on several types of SiPMs, to assess the main phenomena and the deterioration mechanisms, aiming to a more radiation tolerant SiPM design.
In this work we irradiated several types of SiPM structures, produced in FBK (Trento, Italy), with 40 keV X-rays, at several doses, up to 100 kGy (in silicon), performing both online measurements (after each irradiation step) and offline functional characterization, after one month of room temperature annealing. The SiPMs are made with many different technologies, in particular different layouts, junction polarities, internal structures and starting materials. We studied the variation in the reverse current–voltage curves, distinguishing the effects on multiplied and not-multiplied current components, the primary dark count rate, the correlated noise probabilities and photon detection efficiency. Comparing all the measurement results, knowing the internal structure and the fabrication processes, we were able to extract and distinguish different deterioration mechanisms, also supported by TCAD simulations on the different effects of ionizing radiation inside the microcells
NUV-HD SiPMs with Metal-filled Trenches
No full textIn this contribution we would like to present a breakthrough improvement of the optical crosstalk between SPADs in SiPMs. In the framework of a collaboration between FBK and Broadcom we developed narrow metal-filled trenches that greatly suppress the optical crosstalk while maintaining a high fill factor and, in turn, photon detection efficiency. In particular, the new metal in trench detector (NUV-HD-MT) features an internal crosstalk almost 10 times lower than previous NUV-HD FBK SiPMs and can operate up to 17 V of excess bias voltages without any divergence of the correlated noise. The higher operating bias compensates the small loss in fill factor due to the insertion of the metal layer in the trenches and allows the NUV-HD-MT to reach PDE in excess of 60% with 40 μm cells. Together with a SiPM layout optimized for timing, the extended bias range allows to operate the detector with higher gain and low level of correlated noise, improving the CTR performance below 90 ps using 4x4 mm2 detectors coupled to 3x3x5 mm3 LYSO:Ce crystals and readout by a conventional front-end. The characteristics described above allow this detector to be considered as a good candidate for the upgrade of ToF-PET machines
Evaluation of 10 × 10 mm2 Linearly Graded SiPMs for High-resolution Small-animal PET
No full textPosition-sensitive SiPMs (PS-SiPMs) are promising photodetectors for high-resolution small animal positron emission tomography (PET) scanners. With the ultimate goal of developing a 0.5 mm resolution small-animal PET scanner, we developed 10 x 10 mm 2 linearly graded SiPMs (LG-SiPMs), a type of PS-SiPMs. In this paper, the performance of depth-of-interaction encoding dual-ended readout detectors based on these LG-SiPMs and LYSO arrays with a pitch of 0.5 mm and a thickness of 20 mm were evaluated. The flood histogram shows the crystal elements were clearly resolved. The average energy resolution and timing resolution across the LYSO array are 22.3 ± 9.4% and 0.99 ± 0.02 ns, respectively
First Demonstration of the Use of LG-SiPMs for Optical Readout of a TPC
No full textThis paper describes a new method for optical readout of Time Projection Chambers (TPCs), based on the Linearly Graded Silicon Photomultiplier (LG-SiPM). This is a single photon-sensitive detector with excellent timing and 2D position resolution developed at Fondazione Bruno Kessler, Trento (FBK). The LG-SiPM produces time-varying voltage signals that are used to reconstruct the 3D position and energy of ionisation tracks generated inside the TPC. The TPC used in this work contained room-temperature CF4 gas at a pressure of 100 mbar, with two THGEMs to produce secondary scintillation light. A collimated 241Am source (Qα = 5.486 MeV) was used to produce the ionisation tracks. The successful reconstruction of these tracks is demonstrated, and the consistency of the methodology characterised through varying the geometry of the tracks within the TPC. Energy reconstruction and deposition studies are also described, demonstrating the feasibility of the LG-SiPM as a potential option for optical TPC readout
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